Wells – Processes – Distinct – separate injection and producing wells
Reexamination Certificate
2001-10-13
2003-11-25
Tsay, Frank (Department: 3672)
Wells
Processes
Distinct, separate injection and producing wells
C166S265000
Reexamination Certificate
active
06651741
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the oil and gas industry. The Abrasive Hydrojet Perforation Technology offers an effective means to communicate the wellbore with the target formation and to achieve more effective completion due to an increase of flow area, bypassing the damage in a near-wellbore zone and reduction of the compressive stresses The invention represents a new method of treatment of a near-well zone of the producing formation with a combination of chemical treatment.
It is known that flow from productive zones can be increased by slotting and chemical treatment. Slotting allows redistribution of the mechanical stresses in the near well zone, while chemical treatment allows increased productivity of the wells. However, the first method is very labor consuming and requires high costs. In order to shot three feet of the productive interval some time it is necessary to spend up to three hours of pumping unit operation, which is an expensive operation. The chemical action also treats the near well zone, but it requires a primary opening of the formation and does not remove a zone of support pressure which is a main reason of locking of the passages for fluid flow into the well. The first method is very efficient and increases the productivity of wells on average several times, however it is expensive. In order to provide maximum effectiveness or completely restore the potential productivity of wells, it is usually necessary to provide a subsequent treatment with formation-treating reagents.
Some of known solutions are disclosed for example in U.S. Pat. No. 3,965,982; patent document WO94/05898; SU 10472234; SU 1031263; SU 1167925; “Method Recommendations for Increase of Permeability of near Well Zone by slot Loosening” by Ministry of Geology USSR, PTO “SEIMORGEOLOGIA”, L., 1984; I. N. Ivanov, et al “Flow-in of Fluid to Well with the Use of Various Methods of Opening of Productive Formations”, Geophysical Magazine, 1984, no. 5; V. A. Sidorovski “Opening of Formations and Increase of Productivity of Wels”, M., Ndera, 1978, P111; “Method of Recommendations of Increase of Permeability of near Well Zone with Slot Loosening”, Nii Geology Arctics, Mingeologii USSR, L. 1979.
The method disclosed in SU1167925 is the closest to the present invention. It is a combined method for the increase of productivity, which includes slotting of the well and cyclic acid formation treatment. The slotting is performed in accordance with known “classic” recommendations in order to obtain a maximum possible effect, while the cyclic acid treatment is performed also in accordance with the known method described in the above mentioned documents, for a depth which is not less than 5 diameters of the well, so as to attempt to completely use its possibilities without the consideration of the results of slotting or control of the results of each cycle. The cyclical “periodic” treatment of a well was performed by a reagent solution whose volume was determined from a mass and porosity of rock adjoining a shaft of the well, at a distance of approximately two diameters from the well. Each cycle of treatment is performed by pressing of a calculated volume of solution into the formation to be treated, which is preliminarily limited from above and from below by packers. The treatment in some sense is performed blindly, the results were evaluated in accordance with a change of productivity of the well. The cycles of treatment continued until the time when repetition did not lead to a change in productivity.
It has been shown from practice that this method which includes a complete slotting with a subsequent complete treatment with technological reagents has a universal action on the formation and provides an increase of well productivity, an equalization of a profile of advancement of a front of water pumped into a formation for maintaining of the formation pressure, an increase of the oil yield of the formation. Because of these advantages this method has been widely utilized. It also has been used during exploration and drilling of new wells. Moreover, it was made possible with this method to explore and efficiently use wells in low-production formations of Western Siberia in which the oil flow is less than 30 bbl per day. This method therefore is efficient. However, this method, similarly to the other methods has a limitation as to its possibility and efficiency. It is expensive, labor consuming and does not guarantee obtaining of the maximum possible increase of well productivity. The method is used without consideration of negative action of elevated stress concentrations, which are formed near the wellbore.
It is known that the maximum stresses in the near well zone are generated within one diameter of the well or approximately 0.6 ft., and the maximum stress directly adjoins the walls of the well (FIG.
1
). The plastic zone in this case can be not considered, since in accordance with the calculation its width at the depth of 10,000 ft. is only 0.03 ft. It is also known that during the process of the drilling of wells, even after carrying out slotting, a zone of support pressure remains near it. The slotting removes only a part of these stresses, which is equivalent to a reduction of depth of the well approximately 1.5 times. During slotting at the depth of 10,000 ft. it is equivalent to a reduction of stresses to the depth of 6,600 ft. However, the mode and parameters of acid treatment (or treatment with other reagents, such as technological compositions) nowadays are determined without consideration of negative influence of the remaining stresses near the well. The zone of support pressure, which remains around the well, is not taken into consideration and parameters of treatment with technological compositions are calculated from the condition of action of a uniform supply of active technological solution per volume unit of a formation.
However, experimental observations and analytical investigations showed that the influence of zone of support pressure near the well is significant. If this influence is not taken into consideration, false conclusions can be made with respect to the productivity of the wells. Based on the results of the treatment, it is considered that a low oil yield from a formation can be explained by a week natural permeability of the formation itself, while a real cause is the reduction of permeability only within limits of the zone of support stresses, caused by stress concentration beyond the wellbore.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to reduce labor consumption and cost of treatment of a well, without a reduction of efficiency of treatment, time of use of wells, and gas/oil yield of productive formations.
In keeping with these objectives and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method for increasing production of oil, gas and hydrogeological wells, which includes Abrasive Hydrojet Perforation Technology (AHPT) and a cyclical treatment of a near well zone with a formation treating reagent, with cutting of slots, determination of a productive zone, and a corresponding volume of a treating technological composition, and introduction (pressing through) of the volume into a formation to be treated, in which in accordance with the present invention the method is performed in two stages so that in the beginning a partial Abrasive Hydrojet Perforation of a near wellbore zone is performed so as to redistribute stresses, and then a remaining part of the support stresses is removed by a cyclical treatment of a well with a formation treating reagent with its control in accordance with the density of the formation to be treated and with a corresponding correction.
The following is a short summary of the benefits, improvements and the most promising applications of Abrasive Hydrojet Perforation technology:
The Abarsive Hydrojet Perforation Technology (AHPT) slotting provides a very precise, reliable and controllable method to establ
Bassin Yakov
Goldstein Boris
Grebennikov Valentin T.
Ivanov Anatoly N.
Marmorshteyn Leon M.
1407580 Ontario Inc.
Tsay Frank
Zborovsky I.
LandOfFree
Method of increasing productivity of oil, gas and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of increasing productivity of oil, gas and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of increasing productivity of oil, gas and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3158274